Elevated, passive continental margins:: Long-term highs or neogene uplifts?: New evidence from West Greenland
Elevated, passive continental margins:: Long-term highs or neogene uplifts?: New evidence from West Greenland
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DOI：
10.1016/j.epsl.2006.05.036
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发表时间：
2006-08-15
影响因子：
5.3
通讯作者：
Lidmar-Bergstrom, Karna
中科院分区：
文献类型：
--
作者：
Japsen, Peter;Bonow, Johan M.;Lidmar-Bergstrom, Karna
人们通常认为，隆起的被动大陆边缘自裂谷期以来一直处于隆起状态。在许多地区，例如斯堪的纳维亚半岛，隆升运动的时间和程度很难确定，因为隆升地区几乎完全由古变质岩组成。然而，西格陵兰保存的中新生代沉积和火山记录使其成为研究被动大陆边缘隆升的关键区域。我们将磷灰石裂变径迹分析数据与地貌分析相结合，研究了西格陵兰岛不同地质区域的景观发展情况。研究表明，西格陵兰岛现今的山脉（北纬65-71度）是新生代三个隆升和侵蚀阶段的最终结果。第一个阶段开始于36 - 30 Ma之间，在渐新世-中新世期间形成了一个平坦的表面。这一表面被重新激活的断层所抵消，导致巨锁在11 - 10 Ma和7 - 2 Ma之间的两个阶段中倾斜并上升到今天的高度，最高可达2英寸。这些新近纪晚期的隆升阶段比裂谷作用晚了约5000万年，比格陵兰岛西部的海底扩张晚了约3000万年，而第一个阶段比格陵兰岛冰川作用早了约300万年。西格陵兰岛和其他大陆裂谷边缘在形态上的相似性表明，裂谷侧翼抬升到今天的高度可能往往是在裂谷作用显著后发生的。被动边缘隆升运动的区域性及其与活动板块边界的相当距离表明，其成因机制必须位于地壳深部或上地幔，在那里地壳和岩石圈的厚度在较短的距离内发生了很大的变化。(c) 2006 Elsevier B.V.版权所有
It is commonly assumed that elevated, passive continental margins have remained uplifted since the time of rifting. In many areas, e.g. Scandinavia, the timing and extent of uplift movements are difficult to determine because the uplifted area consists almost exclusively of ancient metamorphic rocks. However, the preserved Mesozoic-Cenozoic sedimentary and volcanic record of West Greenland makes this a key area for studying the uplift of passive continental margins.We have combined apatite fission-track analysis data with landform analysis to investigate the development of West Greenland landscapes across areas with substantially different geology. We show that the present-day mountains of West Greenland (65-71 degrees N) are the end result of three Cenozoic phases of uplift and erosion. The first phase that began between 36 and 30 Ma led to the formation of a planation surface during the Oligocene-Miocene. This surface was offset by reactivated faults, resulting in megablocks that were tilted and uplifted to present-day attitudes of up to 2 kin in two phases that began between 11 and 10 and between 7 and 2 Ma. These late Neogene uplift phases postdate rifting by c. 50 million years and sea-floor spreading west of Greenland by c. 30 million years, while the first of these phases predates onset of glaciation in Greenland by c. 3 million years.The similarity in morphology between West Greenland and other rifted continental margins suggests that uplift of rift flanks to present-day elevations may often post-date rifting significantly. The regional nature of the uplift movements along passive margins and their considerable distance from active plate boundaries suggest that the causal mechanisms must be located in the deep crust or the upper mantle where the thickness of the crust and lithosphere changes substantially over a short distance. (c) 2006 Elsevier B.V. All rights reserved.